Hot water heater with self-powered automatic pilot light

ABSTRACT

Hot water heater system (such as, for example, a gas-powered hot water heater system) that includes a self-powered automatic pilot light and which is not connected to any external source of electrical power.

TECHNICAL FIELD

This disclosure relates to a hot water heater system (such as, for example, a gas-powered hot water heater system) that includes a self-powered automatic pilot light.

BACKGROUND

Conventional hot water heaters include a storage type hot water heater and a tankless type hot water heater.

Most household and commercial hot water heaters in use today are the storage-type hot water heaters, which have changed little in decades. They consist of a water tank that has a standing pilot light (i.e. a pilot light that is always on) and a single thermo-mechanical bimetallic gas valve underneath. When the water in the tank cools to below the set temperature threshold of a thermostat in the thermo-mechanical gas valve, the cooling causes the thermo-mechanical valve to open which allows the gas to flow to the main burner and be lighted by the standing pilot light. When the water temperature in the tank rises and satisfies the set temperature threshold of the thermostat in the thermo-mechanical gas valve, the valve is then closed. Such mechanism is entirely mechanical, with no electrical power required.

Conventional storage-type hot water heaters also generally include a safety mechanism that is similarly mechanical in nature. The safety mechanism includes a spring loaded, normally closed valve that prevents the gas (which flows though the opened thermo-mechanical valve) from flowing to the main burner. The spring-loaded, normally closed valve may be held open by the heat of the pilot (e.g. via a thermocouple) after the pilot light is manually lit. If for any reason the pilot light fails or blows out, the flow of unlit gas must be stopped, and so the loss of the heat from the pilot light causes the safety mechanism to be triggered, allowing the spring to force close the safety valve, stopping the flow of gas to the entire system.

While such storage-type hot water heaters are safe, consistent, long lasting, and relatively inexpensive, there is a significant drawback in that storage-type hot water heaters require a standing pilot light to be lit 24 hours a day. Thus, over the course of time, a significant amount of gas may be consumed in order to keep the pilot light lit at all times, and when multiplied by the millions of hot water heaters currently in use, the amount of gas consumed becomes extremely large. Indeed, it is estimated that if all of the pilot lights on all of the gas fired storage hot water heaters in use today were eliminated, it will save consumers in the United States $1.66 billion dollars each year, and it will save the United States over 132 billion cu. ft. of natural gas and/or propane (both of which are non-renewable energy sources) each year.

The other type of conventional hot water heater is the instant, tankless type hot water heater. These are tankless devices that turn on as soon as water flow is detected. Energy is saved by not having a tank of water to keep hot 24 hours a day, although it is estimated that the savings for the typical consumer switching to the tankless type hot water heaters is only about $70-$80 per year.

However, tankless type hot water heaters have several drawbacks. For example, they have a very large initial cost, especially in a retrofit configuration. Further, in addition to purchasing the unit itself, the total expense is significantly increased by the necessity for re-piping in a large gas line to keep up with the high gas draw, as well as the possibility of having to re-pipe the water lines. In addition, an external electrical service or power source (such as connection to external electrical main lines or external power outlets) may be required, which is typically not necessary in the older storage type units and may lead to the entire hot water heater becoming un-usable and non-functional if there is a loss of external power (such as during a power blackout). Another drawback is that some units will give a ‘cold water sandwich’ (that is, output cool, or even cold, water) when the hot water tap is turned on, until the hot water heater unit cycles on and starts to produce hot water. In addition, there are going to be many instances where it is not feasible to install tankless type hot water heaters, especially in older buildings.

There remains a need for a hot water heater that is fail-safe, long lasting, relatively inexpensive, has similar connections to traditional storage tank type hot water heaters (so that little or no piping changes are necessary), but that also eliminates the standing pilot light (in contrast to the conventional storage type hot water heaters that require a standing pilot light), and that also requires no external power (in contrast to the conventional tankless type hot water heaters that require external power).

SUMMARY

In an aspect of this disclosure, there is provided a hot water heating system that includes a self-powered automatic pilot light.

In another aspect, the pilot light only remains lit when there is a need to heat water in a water tank. For example, the pilot light only remains lit when the temperature of the water in the water tank is below a given threshold.

In another aspect, the hot water heating system including the automatic pilot light is self-powered and is not connected to an external source of electrical power.

In another aspect, a water heating system comprises: a water tank; a main burner configured to heat water in the water tank; and a pilot light configured to ignite fuel to light the main burner. Moreover, a first thermo-mechanical valve unit monitors temperature of the water and determines whether the temperature of the water is below a first threshold, and permits fuel to flow to the pilot light, when the first thermo-mechanical valve unit determines that the temperature of the water is below the first threshold. An ignition unit ignites the pilot light, when the first thermo-mechanical valve unit permits fuel to flow to the pilot light. A second thermo-mechanical valve unit monitors temperature near the pilot light and determines whether the pilot light is ignited, and permits fuel to flow to the main burner and be ignited by the pilot light, when the second thermo-mechanical valve unit determines that the temperature near the pilot light is above a second threshold.

In another aspect, the first thermo-mechanical valve unit prevents fuel from flowing to the pilot light, and thereby causing the pilot light to be extinguished, when the first thermo-mechanical valve unit determines that the temperature of the water is equal to or greater than the first threshold.

In another aspect, the second thermo-mechanical valve unit prevents fuel from flowing to the main burner, and thereby shutting off the main burner, when the second thermo-mechanical valve unit determines that the ambient temperature near the pilot light is equal to or below the second threshold.

In another aspect, a switch closes when the first thermo-mechanical valve unit permits fuel to flow to the pilot light. Moreover, an electronic controller controls the ignition unit to ignite the pilot light, when the electronic controller determines that the switch is closed.

In another aspect, a solenoid piston opens a safety valve of the first thermo-mechanical valve unit for a predetermined time period to permit fuel to flow to the pilot light. The electronic controller controls the solenoid piston to open the safety valve for the predetermined time period, when the electronic controller determines that the switch is closed.

In another aspect, after the solenoid piston is deactivated after the predetermined time period, a thermocouple powered by heat from the pilot light keeps the safety valve open to continue permitting fuel to flow to the pilot light after the solenoid piston is deactivated.

In another aspect, a battery supplies electronic power to the electronic controller, the ignition unit, and the solenoid piston.

In another aspect, a thermopile converts heat generated from the ignited main burners into electrical energy to recharge the battery.

In another aspect, a solar cell converts light generated from the ignited main burners into electrical energy to recharge the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other aspects, features and advantages can be more readily understood from the following detailed description with reference to the accompanying drawings wherein:

FIG. 1 shows a block diagram of a hot water heater system including a self-powered automatic pilot light, according to an exemplary embodiment;

FIG. 2 shows a schematic diagram of an electrical system of a hot water heater system, according to an exemplary embodiment;

FIG. 3 illustrates a flowchart of a method performed by a hot water heater system including a self-powered automatic pilot light, such as system 100 illustrated in FIG. 1, according to an exemplary embodiment;

FIG. 4 shows a block diagram of a hot water heater system including a self-powered automatic pilot light, according to another exemplary embodiment;

FIG. 5 illustrates a flowchart of a method performed by a hot water heater system including a self-powered automatic pilot light, such as system 400 illustrated in FIG. 4, according to another exemplary embodiment.

DETAILED DESCRIPTION

In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. In addition, a detailed description of known functions and configurations will be omitted when it may obscure the subject matter of the present invention.

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, there is described a hot water heater system (such as, for example, a gas-powered hot water heater system) that includes a self-powered automatic pilot light.

For example, FIG. 1 shows schematically a hot water heater system 100 that includes a self-powered automatic pilot light. As illustrated in FIG. 1, the hot water heater system 100 includes a water tank 10 containing water, a main burner 60 configured to heat the water in the water tank, and a pilot light 30 configured to ignite fuel to light the main burner. The system also includes a first thermo-mechanical valve (TMV) unit A, an ignition unit 40, and a second thermo-mechanical valve (TMV) unit B. TMV Unit A and TMV Unit B are strictly thermo-mechanical devices, and are not electrically powered.

TMV Unit A 20 includes a probe or sensor 20 a connected to the water tank 10, and which may extend into the interior of the water tank 10 and/or contact the water inside the water tank 10. The probe 20 a is connected to a thermostat 20 b that, together with the probe 20 a, determine the temperature of the water tank 10 and/or the water inside the water tank 10, and determine whether the measured temperature is lower than a first threshold that is set or stored in the thermostat 20 b. If the measured temperature is indeed lower than the first threshold, TMV Unit A opens a main valve 20 d that permits a fuel supply received via input pipe 20 c to flow out through output pipe 20 e and flow towards the pilot light. In this way, pilot light 30 has a supply of fuel so that the pilot light can be lit, by the ignition unit 40 described below. Thus, TMV Unit A determines whether the temperature of the water in the water tank 10 is below a first threshold, and permits fuel to flow to the pilot light 30, when a first temperature measuring unit (probe 20 a and/or thermostat 20 b) of TMV Unit A determine that the temperature of the water is below the first threshold.

The ignition unit 40 may include a sparker and sparker controller, and is configured to ignite the pilot light, when the TMV Unit A opens the main valve 20 d and permits fuel to flow to the pilot light 30. Thus, the pilot light 30 is not a standing pilot light that is constantly lit. Instead, pilot light 30 is an automatic pilot light that is only lit by the ignition unit when the TMV Unit A opens the main valve 20 d and permits fuel to flow to the pilot light 30 (i.e. the pilot light 30 is only lit when the TMV Unit A determines that the temperature of the water in the water tank 10 is below a first threshold). The operation of the ignition unit 40 will be described in further detail below.

TMV Unit B 50 includes a probe or sensor 50 a that is placed near the pilot light 30 and detects the ambient temperature near the pilot light 30. The probe 50 a is connected to a thermostat 50 b that, together with the probe 50 a, determine the ambient temperature near the pilot light 30, and determine whether the ambient temperature is above a second threshold that is set or stored in the thermostat 50 b. If the measured ambient temperature is indeed above the second threshold, TMV Unit B determines that the pilot light 30 is lit, opens a main valve 50 d that permits a fuel supply received via input pipe 50 c to flow out through output pipe 50 e and flow towards the pilot light 30 and towards the main burner 60. The pilot light 30 will then light the fuel exiting the output pipe 50 e and light the main burner 60 in order to heat the water in water tank 10. Thus, TMV Unit B determines whether the pilot light is ignited (by determining whether the ambient temperature near the pilot light is above a second threshold), and permits fuel to flow to the main burner 60 and be ignited by the pilot light 30, when a second temperature measuring unit (probe 50 a and/or thermostat 50 b) determines that the ambient temperature near the pilot light 30 is above the second threshold.

As a result of the aforementioned steps, the lit main burner 60 will heat the water in the water tank 10. Eventually, the temperature of the main tank 10 (or water in the main tank 10) will increase to satisfy the first threshold set in the thermostat 20 b of the TMV Unit A 20. When the first temperature measuring unit (probe 20 a and/or thermostat 20 b) determines that the temperature of the water is equal to or greater than the first threshold, TMV Unit A will close the main valve 20 d to prevent fuel from flowing out of the output pipe 20 e to the pilot light 30. Without this supply of fuel to the pilot light 30, the pilot light 30 will be extinguished.

Thereafter, the ambient temperature around the extinguished pilot light will decrease to satisfy the second threshold set in the thermostat 50 b of the TMV Unit B 50. When the second temperature measuring unit (probe 50 a and/or thermostat 50 b) determines that the ambient temperature near the pilot light is equal to or below the second threshold, TMV Unit B will close the main valve 50 d to prevent fuel from flowing out of the output pipe 50 e to the main burner 60. Without this supply of fuel to main burner 60, the main burner 60 will be extinguished.

It should be noted that the first temperature threshold corresponding to the thermostat of TMV Unit A is variable, based on user adjustment of an interface (e.g. thermostat knob) of TMV Unit A in order to set a desired water temperature. On the other hand, the second temperature threshold corresponding to the thermostat of TMV Unit B is generally pre-set by the manufacturer of TMV Unit B, and is generally not user settable.

All of the aforementioned operations (apart from ignition by the ignition unit 40) are strictly thermo-mechanical operations that do not require any source of electrical power.

Turning now to FIG. 2, there are described further aspects of the hot water heating system 100 of FIG. 1. In particular, a safety system and self-powered electrical subsystem of the aforementioned hot water heating system 100 of FIG. 1 are described.

As seen in FIG. 2, a switch 80 is connected to the main valve 20 d of the TMV Unit A 20. The switch 80 may be comprised of a reed switch, magnetic switch, miniature snap-action switch, micro switch, and other types of switches known in the art. The switch 80 is configured to close when TMV Unit A opens the main valve 20 d (i.e. permits fuel to flow to the pilot light 30). Note that at this point in time the pilot light 30 may not yet be lit. An electronic controller 81 detects the closing of the switch 80 and takes steps to light the pilot light 30. In particular, the electronic controller controls the ignition unit (including sparker controller 40 a which in turn controls sparker 40 b) to spark to ignite the pilot light 30, when the electronic controller determines that the switch 80 is closed. The electronic control 81 also controls a solenoid piston 82 to open a safety valve 90 for a predetermined time period (such as 60 seconds), to ensure that fuel flows from the opened valve 20 d through the entire output pipe 20 e towards the pilot light 30 to be lit by the ignition unit 40.

That is, output pipe 20 e of TMV Unit A may include a spring loaded, normally closed safety valve 90 that prevents the gas (which flows though the opened main valve 20 d) from flowing to the pilot light. The spring-loaded, normally closed valve may be held open by the heat of the pilot after the pilot light is lit. For example, the heat of the pilot light flame can be used to generate electrical energy with a thermocouple (not shown), and the generated energy may be used to power a solenoid to force open the spring-loaded, normally closed safety valve 90, thereby allowing the gas to flow from the opened thermo-mechanical valve to the pilot light. If for any reason the pilot light fails or blows out, the flow of unlit gas must be stopped, and so the loss of the heat from the pilot light causes the safety mechanism to be triggered, allowing the spring to force close the safety valve 90, stopping the flow of gas to the pilot light.

According to the aspects of this embodiment, when the pilot light needs to be lit, the electronic controller: (1) controls a solenoid piston 82 to open the safety valve 90 for a predetermined time period (e.g. 60 seconds) to permit fuel to flow through output pipe 20 e to the pilot light 30 and (2) controls the ignition unit 40 to light the pilot light with use of the fuel flowing through output pipe 20 e. The electronic controller does both (1) and (2) only when the electronic controller determines that the switch 80 is closed (which occurs when TMV Unit A opens main valve 20 d to allow fuel to enter output pipe 20 e). After the solenoid piston 82 is deactivated by the electronic controller 81 after the predetermined time period has expired, a thermocouple (not shown) powered by heat from the pilot light 30 keeps the safety valve 90 open to permit fuel to keep flowing to the pilot light 30.

Thus, the hot water heating system of this disclosure may use a conventional thermo-mechanical valve unit with the same safety valve that is used in an existing storage type of hot water heater, supplementing it with a solenoid so that the piston of the solenoid is in alignment with a push button of the safety valve. When there is a call for hot water, the solenoid actuates for 60 seconds which causes its piston to push down the safety valve, opening the gas. After 60 seconds, the solenoid shuts down with the spring returning the piston to its at-rest position. The pilot flame will now keep the safety valve open. If there is a flame failure, the safety valve shuts off the gas just as it does with a traditional hot water heater. If there is an electrical failure, the safety valve remains shut. This creates a failsafe environment.

The aforementioned operations of the electronic controller 81, solenoid 82 and ignition unit 40 are the only electrically-power operations of the hot water heating system 100 of this disclosure. Electronic power for operations of the electronic controller 81, solenoid 82 and ignition unit 40 is supplied by the battery 85. In the aspects of this disclosure, a thermopile 84 converts heat generated from the ignited main burner 60 into electrical energy to recharge the battery 85. Instead, or in addition, a solar cell 83 converts light generated from the ignited main burner 60 into electrical energy to recharge the battery 85. The configuration of the solar cell 83 is preferably optimized for generating energy from the portion of the visible light spectrum corresponding to the gas flames emitted from the main burner 60, in order to maximize the recharging abilities of the solar cell 83. Thus, the entire hot water heating system of this disclosure is self powered, since TMV Units A and B are strictly thermo-mechanical devices, and the electronic controller 81, solenoid 82 and ignition unit 40, battery 85, etc., receive power from the ignited main burners 60 via a solar cell or thermopile.

The battery requirements of the hot water heating system of this disclosure are quite modest. Electrical power is only briefly used at the beginning of each cycle to run the sparker which lights the pilot light and to actuate the safety solenoid/valve combination for 60 seconds. Otherwise, the system is thermo-mechanical.

Thus, according to this exemplary embodiment, there is provided a hot water heating system with an automatic pilot light that is only lit when there is a need to heat water in a water tank (i.e. when the temperature of the water in the water tank is below a first threshold). Moreover, the entire system is completed self-powered, and is not connected to an external source of electrical power.

Turning now to FIG. 3, there is shown a flowchart of a method performed by a hot water heating system, such as hot water heating system 100 illustrated in FIG. 1, according to an exemplary embodiment.

First, the thermostats knob of the thermostat 20 b is set to the desired temperature, i.e. the first temperature threshold (S301). Water in the water tank 10 cools (S302). When the water in the tank cools to below the set temperature threshold (S303, Yes), TMV Unit A 20 is triggered which opens the main pilot valve 20 d and feeds fuel such as natural gas or propane to the output pipe 20 e (S304). This action also causes the electronic controller 81 to activate the solenoid piston 82 for a predetermined time period (e.g. 60 seconds) which causes its piston to push down and open the safety valve 90, opening the fuel to flow through the output pipe 20 e to the pilot light 30. The closing of switch 80 also causes the electronic controller 81 to actuate the sparker 40 b, which may be powered by a 12 volt on-board battery 85. (When a flame is evident, the sparker 40 b as is typically designed, automatically stops sparking). If the pilot light does not light in the predetermined time period (S305, No), the sparker 40 b and solenoid 82 are deactivated (S306), and the safety system (e.g. thermocouple) normally powered by the heat of the pilot light will allow the safety valve 90 to close (S307). If the pilot light is lit (S305, Yes), the sparker 40 b and solenoid 82 are deactivated after the predetermined time period (S308), and the safety system (e.g. thermocouple) powered by the heat of the pilot light will keep the safety valve 90 open.

Located near the pilot flame is the temperature sensing means (probe 50 a and thermostat 50 b) of TMV Unit B 50. When the pilot flame is lit, the pilot flame heats the temperature sensing means at TMV Unit B (S309), and once the detected temperature is higher than the second temperature threshold set at thermostat 50 b (S310, Yes), TMV Unit B will cause the main valve 50 d to open to permit fuel to flow through output pipe 50 e towards the main burner 60 to be lit by the pilot light 30 (S311). This in turn heats the water in the water tank 10 (S312). In addition, while the main burner 60 is firing, the light and/or heat created by the flame of the burner recharges the on-board battery 85 to maintain electrical self-sufficiency in the system. The recharging is done by either solar cells 83 within the confines of the tank housing or by converting heat directly to electrical power via a thermopile 84.

Once the tank water is sufficiently heated to satisfy the first threshold temperature set at thermostat 20 a of TMV Unit A 20 (S313, Yes), TMV A will close the main valve 20 d, shutting off the flow of gas to the pilot light 30 (S314) to thereby extinguish the pilot light 30. With no pilot flame near the sensor 50 a of TMV Unit B, the sensor cools down and the thermostat 50 b determines that the ambient temperature around the pilot light drops below the second threshold set at thermostat 50 b. As a result, TMV Unit B will close main valve 50 d, preventing the flow of fuel to main burner 60 and shutting down the main burner 60 (S315).

What follows are illustrative examples of components that can be used to form the various parts of the hot water heating system illustrated in FIGS. 1 and 2 of this disclosure. It should be noted that the following components are merely exemplary, and many variations can be introduced on these examples without departing from the spirit of the disclosure or from the scope of the appended claims. For example, elements and/or features of different examples and illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims.

Thermo-mechanical valve A (TMV Unit A 20): This may be an off the shelf hot water heater controller except the pilot/safety valve is used as a safety valve 90 only. There is a solenoid piston 82 directly above the push button of the safety valve 90 which can push down engaging the push button, holding it open for 60 seconds. This will allow the pilot light 30 to be lit long enough for it to stay open on its own. The main valve is being used as a pilot valve 20 d. In addition, the pilot valve 20 d includes or is connected to a small reed or magnetic switch 80 to indicate the valve position to the controller 81. This is so the controller knows when there is a call for hot water so it can actuate the solenoid 82 and sparker 40 b.

Thermo-mechanical valve B (TMV Unit B 50): This may also be an off-the-shelf hot water heater controller with a few minor modifications. First the pilot/safety valve is not used and is blocked open. Next, the main valve 50 d is modified to function backwards. In other words when the sensor 50 a is heated past the temperature threshold, the valve 50 d opens and when the sensor 50 a cools, the valve 50 d closes. Finally, the temperature sensing means 50 a has a much smaller mass so the valve will react faster. A longer, heavier sensing means is not necessary since there is no immersion in a liquid.

Main Burner 60 and Pilot 30: May be off-the-shelf except they are separated by a few inches with a tube between them to insure the flame can travel from the pilot to the main burner.

Sparker Controller 40 a and Sparker 40 b: May be off-the-shelf D.C. version.

Battery 85: May be off-the-shelf 12 volt rechargeable lead acid typical of what is used in emergency lighting and alarm system backups.

Solar cells 83 or thermopile 84: May be off-the-shelf.

Solenoid A 82: Located above the safety valve 90 push button. It will energize for 60 seconds starting when there is a call for hot water at TMV A. The solenoid 82 piston engages the safety valve 90, opening it for the 60 seconds. After 60 seconds the solenoid 82 is de-energized and the spring returns it to its at-rest position.

Controller/circuit board 81: One purpose of the controller/circuit board is to actuate the solenoid 82 and time its action for 60 seconds. The trigger is the switch 80 located at TMV Unit A 80 which closes every time there is a call for hot water and the valve 20 d at TMV Unit A opens. After 60 seconds, the solenoid 82 is de-energized and the mechanical cycle continues on to fire the main burner 60. If a reset is required, simply turning the temperature dial of thermostat 20 b to cool and then back to hot will trigger the solenoid and sparker once again. Another function of the controller/circuit board is to correct the voltage output of the power producing components to enable recharging of the battery 85 and also to prevent its overcharging.

Turning now to FIG. 4, there is described another exemplary embodiment of this disclosure.

In particular, FIG. 4 shows schematically a hot water heater system 400 that includes a self-powered automatic pilot light. The hot water system 400 illustrated in FIG. 4 is similar to the system 100 illustrated in FIG. 1, and thus similar part numbers have been used in FIG. 4 to label specific parts that are identical to those depicted in FIG. 1.

One difference between hot water heater system of FIG. 4 and that of FIG. 1 is that, in the system 400 of FIG. 4, the plumbing is re-routed so that the two thermo-mechanical valves TMV Unit A 20 and TMV Unit B 50 are fed in series. That is, the output of fuel from the output pipe 20 e-1 of TMV Unit A is fed to both: (1) the pilot light 30, in a similar manner to that described in FIG. 1; and (2) the input pipe 50 c-1 of TMV Unit B. The result is that when the water temperature satisfies (i.e. is greater than) the temperature threshold set at thermostat 20 b, TMV Unit A closes the valve 20 d so that both: (1) the pilot light 30 is extinguished; and (2) no fuel whatsoever is flowing to TMV Unit B, so that the main burner 60 will also be extinguished.

The second embodiment of FIG. 4 has an identical safety system as the first embodiment of FIG. 1, with the addition of one extra feature which will prevent ‘fast cycling’. This is an event which will not occur during normal operation but possibly might happen if the temperature adjustment knob at thermostat 20 b of TMV Unit A is turned to a much higher setting immediately after the hot water temperature has been satisfied and the TMV A has closed. Fast cycling is when TMV Unit A opens to light the pilot but TMV Unit B has not yet cooled enough to close from a previous cycle. This confluence of unusual factors could cause the main valve to be open before the pilot is lit. It is a rare possibility but one that must be addressed to maintain a completely fail-safe environment.

This is addressed with some additional components. The pilot valve 20 d automatically and mechanically latches closed when the hot water temperature at thermostat 20 b is satisfied. Once the main valve 50 d closes as determined by a reed or magnetic switch connected to the main valve 50 d (which indicates valve position of the main valve 50 d), a second solenoid, Solenoid B (not shown) momentarily energizes to unlatch the pilot valve 20 d to allow it to open the next time there is a call for hot water. While the pilot valve 20 d is latched closed, the pilot valve 20 d cannot open under any circumstances, until the main valve 50 d cools and closes-which in turn triggers the Solenoid B to unlatch the pilot valve 20 d. This is a fail-safe method of preventing fast cycling. This safety system can also be applied to the first embodiment if FIG. 1, if desired.

Turning now to FIG. 5, there is shown a flowchart of a method performed by a hot water heating system, such as hot water heating system 400 illustrated in FIG. 4, according to an exemplary embodiment.

The method of FIG. 5 is similar to the method of FIG. 3, except in certain respects. For example, at S501, the thermostats knob of the thermostat 20 b is set to the desired temperature (i.e. the first temperature threshold), and solenoid B activates to unlatch the valve 20 d of TMV Unit A.

Another difference is that, once the tank water is sufficiently heated to satisfy the first threshold temperature set at thermostat 20 a of TMV Unit A 20 (S513, Yes), TMV Unit A will close the valve 20 d (S514) and shut off the flow of gas to both: (1) the pilot light 30, to thereby extinguish the pilot light 30; and (2) the input pipe 50 c-1 of TMV Unit B, to prevent the flow of fuel to main burner 60 to thereby extinguish the main burner 60. Moreover, in S514, the pilot valve 20 d is latched closed.

Further, with no pilot flame near the sensor 50 a of TMV Unit B, the sensor cools down and the thermostat 50 b determines that the ambient temperature around the pilot light drops below the second threshold set at thermostat 50 b. As a result, TMV Unit B will close main valve 50 d (S515). This also results in Solenoid B pulsing to unlatch the pilot valve 20 d of TMV Unit A for the next cycle (S515).

What follows are illustrative examples of components that can be used to form the various parts of the hot water heating system 400 of the embodiment illustrated in FIG. 4. It should be noted that the following components are merely exemplary. The system 400 in the embodiment of FIG. 4 may contain all of the components of the system 100 in the embodiment of FIG. 1, with the following additions.

TMV Unit A 20: There may be an additional mechanical latching mechanism when compared to the embodiment of FIG. 1. This will latch valve 20 d of TMV Unit A closed once the tank water temperature satisfies the temperature threshold set in thermostat 20 b. The mechanical latching mechanism cannot be unlatched until valve 50 d of TMV Unit B 50 closes, at which point solenoid B is momentarily activated to unlatch valve 20 d of TMV Unit A.

TMV Unit B 50: Like TMV Unit A, there may be a switch (e.g. reed or magnetic switch) which acts as a position sensor to the controller 81. This is used to let the controller 81 know that valve 50 d of TMV Unit B has closed, so that the controller 81 can cause solenoid B to pulse unlatching valve 20 d of TMV Unit A (protection against fast cycling).

Controller 81: In the embodiment of FIG. 4, the controller 81 also causes solenoid B to pulse momentarily, once valve 50 d of TMV Unit B closes at the end of the cycle, to unlatch the valve 20 d of TMV Unit A.

Solenoid B: Located at TMV Unit A. Once the tank temperature satisfies the temperature threshold set in thermostat 20 b, TMV Unit A will close valve 20 d and then shortly thereafter and TMV Unit B will close valve 50 d. Once this occurs, the solenoid B is momentarily energized to unlatch the locking mechanism, allowing TMV Unit A to open valve 20 d the next time there is a call for hot water.

According to the embodiments of this disclosure, there is described a hot water heating system that is safe, reliable, and relatively simple, and inexpensive, but has the advantage of electronic ignition, no standing pilot, and a self-sufficient electrical environment with recharging done by either solar cells or thermopile. If all of the conventional storage-type of hot water heaters are taken as a group and converted to the systems of this disclosure, an enormous amount of money and gas may be saved long after the initial, additional investment is amortized.

The aforementioned specific embodiments are illustrative, and many variations can be introduced on these embodiments without departing from the spirit of the disclosure or from the scope of the appended claims. For example, elements and/or features of different examples and illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims. 

What is claimed is:
 1. A water heating system comprising: a water tank; a main burner configured to heat water in the water tank; a pilot light configured to ignite fuel to light the main burner; a first thermo-mechanical valve unit that monitors temperature of the water and determines whether the temperature of the water is below a first threshold, and permits fuel to flow to the pilot light, when the first thermo-mechanical valve unit determines that the temperature of the water is below the first threshold; an ignition unit configured to ignite the pilot light, when the first thermo-mechanical valve unit permits fuel to flow to the pilot light; and a second thermo-mechanical valve unit that monitors temperature near the pilot light and determines whether the pilot light is ignited, and permits fuel to flow to the main burner and be ignited by the pilot light, when the second thermo-mechanical valve unit determines that the temperature near the pilot light is above a second threshold.
 2. The water heating system of claim 1, wherein the first thermo-mechanical valve unit prevents fuel from flowing to the pilot light to thereby extinguish the pilot light, when the first thermo-mechanical valve unit determines that the temperature of the water is equal to or greater than the first threshold; and the second thermo-mechanical valve unit prevents fuel from flowing to the main burner to thereby shut off the main burner, when the second thermo-mechanical valve unit determines that the temperature near the pilot light is equal to or below the second threshold.
 3. The water heating system of claim 1, further comprising: a switch that closes when the first thermo-mechanical valve unit permits fuel to flow to the pilot light; and an electronic controller that controls the ignition unit to ignite the pilot light, when the electronic controller determines that the switch is closed.
 4. The water heating system of claim 3, further comprising: a battery that supplies electrical power to the electronic controller and the ignition unit; and a thermopile that converts heat generated from the ignited main burners into electrical energy to recharge the battery.
 5. The water heating system of claim 3, further comprising: a battery that supplies electrical power to the electronic controller and the ignition unit; and a solar cell that converts light generated from the ignited main burners into electrical energy to recharge the battery.
 6. The water heating system of claim 3, further comprising a solenoid piston that opens a safety valve of the first thermo-mechanical valve unit for a predetermined time period to permit fuel to flow to the pilot light, wherein the electronic controller controls the solenoid piston to open the safety valve for the predetermined time period, when the electronic controller determines that the switch is closed.
 7. The water heating system of claim 6, wherein after the solenoid piston is deactivated after the predetermined time period, a thermocouple powered by heat from the pilot light keeps the safety valve open to continue permitting fuel to flow to the pilot light after the solenoid piston is deactivated.
 8. The water heating system of claim 6, further comprising: a battery that supplies electronic power to the electronic controller, the ignition unit, and the solenoid piston; and a thermopile that converts heat generated from the ignited main burners into electrical energy to recharge the battery.
 9. The water heating system of claim 6, further comprising: a battery that supplies electronic power to the electronic controller, the ignition unit, and the solenoid piston; and a solar cell that converts light generated from the ignited main burners into electrical energy to recharge the battery.
 10. The water heating system of claim 1, wherein the pilot light remains lit while the temperature of the water is below the first threshold.
 11. The water heating system of claim 1, wherein the system is not connected to an external source of electrical power.
 12. A method for heating water in a water tank, performed by a water heating system including a main burner configured to heat the water in the water tank and a pilot light configured to ignite fuel to light the main burner, said method comprising: determining, by a first thermo-mechanical valve unit, whether temperature of the water is below a first threshold, and permitting fuel to flow to the pilot light, when the first thermo-mechanical valve unit determines that the temperature of the water is below the first threshold; igniting, by an ignition unit, the pilot light, when the first thermo-mechanical valve unit permits fuel to flow to the pilot light; and determining, by a second thermo-mechanical valve unit, whether the pilot light is ignited, and permitting fuel to flow to the main burner and be ignited by the pilot light, when the second thermo-mechanical valve unit determines that the ambient temperature near the pilot light is above a second threshold.
 13. The method of claim 12, further comprising: preventing, by the first thermo-mechanical valve unit, fuel from flowing to the pilot light, and thereby causing the pilot light to be extinguished, when the first thermo-mechanical valve unit determines that the temperature of the water is equal to or greater than the first threshold; and preventing, by the second thermo-mechanical valve unit, fuel from flowing to the main burner, and thereby shutting off the main burner, when the second thermo-mechanical valve unit determines that the ambient temperature near the pilot light is equal to or below the second threshold.
 14. The method of claim 12, further comprising: closing a switch when the first thermo-mechanical valve unit permits fuel to flow to the pilot light; and controlling the ignition unit, by an electronic controller, to ignite the pilot light, when the electronic controller determines that the switch is closed.
 15. The method of claim 14, further comprising: supplying electronic power, by a battery of the system, to the electronic controller and the ignition unit; and converting, by a thermopile of the system, heat generated from the ignited main burners into electrical energy to recharge the battery.
 16. The method of claim 14, further comprising: supplying electronic power, by a battery of the system, to the electronic controller and the ignition unit; and converting, by a solar cell of the system, light generated from the ignited main burners into electrical energy to recharge the battery.
 17. The method of claim 14, further comprising: opening, by a solenoid piston, a safety valve of the first thermo-mechanical valve unit for a predetermined time period to permit fuel to flow to the pilot light, wherein the electronic controller controls the solenoid piston to open the safety valve for the predetermined time period, when the electronic controller determines that the switch is closed.
 18. The method of claim 17, wherein after the solenoid piston is deactivated after the predetermined time period, a thermocouple powered by heat from the pilot light keeps the safety valve open to continue permitting fuel to flow to the pilot light after the solenoid deactivates.
 19. The method of claim 17, further comprising: supplying electronic power, by a battery of the system, to the electronic controller, the ignition unit, and the solenoid piston; and converting, by a thermopile of the system, heat generated from the ignited main burners into electrical energy to recharge the battery.
 20. The method of claim 17, further comprising: supplying electronic power, by a battery of the system, to the electronic controller, the ignition unit, and the solenoid piston; and converting, by a solar cell of the system, light generated from the ignited main burners into electrical energy to recharge the battery. 